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Every calculation you need, in one place

Instant, practical tools for math, personal finance, small business, health, and everyday decisions — including pricing, profit, cash flow, and unit conversions. No sign-up. No ads.

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Percentage Calculator

Percent of, percent change, and reverse percentage.

Tip Calculator

Split the bill and calculate tip per person.

Discount Calculator

Find the sale price after any percentage discount.

Health Calculator

BMI, ideal body weight, and daily calorie needs in one place.

Compound Interest

Future value with contributions and compounding.

Mortgage Calculator

Monthly payment with taxes, insurance, PMI, HOA, and full amortization.

Geometry Calculator

Triangle area, perimeter, Pythagorean theorem, and circle calculations.

Statistics Calculator

Mean, median, mode, range, and standard deviation.

Tax Calculator

Estimate 2026 US federal income tax, effective rate, and marginal bracket.

Car Loan Calculator

Monthly car payment with down payment, trade-in, and sales tax.

Graphing Calculator

Plot any math function — polynomials, trig, logs, and more.

Length Converter

Convert meters, km, miles, feet, inches and more.

Temperature Converter

Convert between Celsius, Fahrenheit, and Kelvin.

Volume Converter

Convert liters, gallons, cups, fluid ounces, and more.

Time Converter

Convert seconds, minutes, hours, days, weeks, and years.

Browse All Tools

Percentage CalculatorPopular
Percent of, percent change, and reverse percentage.
Open
Tip CalculatorPopular
Split the bill and calculate tip per person.
Open
Discount CalculatorPopular
Find the sale price after any percentage discount.
Open
GST / VAT Calculator
Add or remove tax from any amount instantly.
Open
Health CalculatorPopular
BMI, ideal body weight, and daily calorie needs in one place.
Open
Compound InterestPopular
Future value with contributions and compounding.
Open
Mortgage CalculatorPopular
Monthly payment with taxes, insurance, PMI, HOA, and full amortization.
Open
Loan EMI Calculator
Monthly payment with amortization summary.
Open
Scientific Calculator
Roots, powers, factorials, combinations, and logarithms.
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Fraction Calculator
Add, subtract, multiply, and divide fractions.
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Ratio Calculator
Simplify ratios and solve proportions.
Open
Geometry CalculatorPopular
Triangle area, perimeter, Pythagorean theorem, and circle calculations.
Open
Statistics CalculatorPopular
Mean, median, mode, range, and standard deviation.
Open
GPA Calculator
Calculate GPA from letter grades and credit hours.
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Tax CalculatorPopular
Estimate 2026 US federal income tax, effective rate, and marginal bracket.
Open
Profit Margin & Markup
Calculate gross profit, margin, markup, and target selling price.
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Break-Even Calculator
Estimate break-even units and sales revenue from costs and price.
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Service Pricing Calculator
Estimate an hourly service rate from pay, overhead, and billable hours.
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Product Pricing Calculator
Price products to account for unit costs, selling fees, and margin.
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Cash Flow Forecast
Forecast ending cash from expected receipts and payments.
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Return on Investment (ROI)
Estimate net gain, ROI percentage, total cost, and return multiple.
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Customer Acquisition Cost
Measure average acquisition spend per new customer.
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Customer Lifetime Value
Estimate customer lifetime revenue and gross profit.
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Sales Commission Calculator
Estimate commission from a base rate and marginal sales bonus.
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Sales Tax Calculator
Estimate state and local sales tax and the tax-inclusive total.
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Car Loan CalculatorPopular
Monthly car payment with down payment, trade-in, and sales tax.
Open
Graphing CalculatorPopular
Plot any math function — polynomials, trig, logs, and more.
Open
Length ConverterPopular
Convert meters, km, miles, feet, inches and more.
Open
Weight Converter
Convert kg, lb, oz, grams, and more.
Open
Temperature ConverterPopular
Convert between Celsius, Fahrenheit, and Kelvin.
Open
Speed Converter
Convert mph, km/h, m/s, knots and more.
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Area Converter
Convert square meters, feet, acres, hectares.
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Data Storage Converter
Convert bits, bytes, KB, MB, GB, and TB.
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Volume ConverterPopular
Convert liters, gallons, cups, fluid ounces, and more.
Open
Time ConverterPopular
Convert seconds, minutes, hours, days, weeks, and years.
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Pressure Converter
Convert Pa, bar, psi, atm, mmHg, and more.
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Energy Converter
Convert joules, calories, kWh, BTU, and more.
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Fuel Economy Converter
Convert mpg, L/100km, km/L and more.
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Date Difference
Find difference between two dates in days & weeks.
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Free Online Calculators & Converters

calctoolkit is a free collection of online calculators and unit converters for everyday math, finance, health, and science. Every tool runs entirely in your browser — results appear instantly with no loading, no sign-up, and no ads.

Our financial and small-business calculators cover mortgages, loans, compound interest, tax estimation, car payments, GST/VAT, pricing, profit margins, break-even analysis, cash flow, ROI, customer metrics, sales commission, and sales tax. The health calculators include BMI, ideal body weight, and daily calorie needs. For students, the math tools handle percentages, fractions, ratios, statistics, geometry, and GPA.

The unit converters handle length, weight, temperature, speed, area, volume, pressure, energy, data storage, fuel economy, and time — covering both metric and imperial systems. Use the date difference calculator to find the number of days between any two dates.